Fiber-optic channel selecting apparatus

ABSTRACT

An apparatus for selectively coupling fiber optic lines comprises an optical input selection device, an optical output selection device, and a rotatable coupling mechanism interconnecting the optical input selection device and the optical output selection device. The optical input selection device is rotatable about a first central axis, and comprises a first input end and a first output end. The first input end is disposed collinearly with the first central axis, and the first output end is disposed at a radially offset distance from the first central axis. The optical output selection device is rotatable about a second central axis, and comprises a second input end and a second output end. The second input end is disposed at a radially offset distance from the second central axis, and the second output end is disposed collinearly with the second central axis. Rotation of the coupling mechanism causes rotation of the first output end and the second input end.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of the U.S. patentapplication Ser. No. 10/077,723, filed on Feb. 14, 2002 now U.S. Pat.No. 6,950,568.

FIELD OF THE INVENTION

The present invention relates generally to the coupling of selectedinput and output lines or channels through which optical signals aredirected, and to the routing of optical signals to and from such linesor channels. More specifically, the present invention relates to thedesign and use of a device adapted to effect selection and couplingthrough coordinated mechanical indexing movements and/or the use ofoptical fiber bundles whose ends are exposed to a detector. Such adevice provides advantage in a wide variety of fields of application,particularly in applications involving the generation and transmissionof analytical information. Specific fields of use include thepreparation, sampling and analyzing of soluble materials as well as thetesting of other fluids and solid materials exhibiting opticalcharacteristics.

BACKGROUND OF THE INVENTION

Optical transport techniques are often utilized to direct a beam orpulse of light from a light source to a test site and, subsequently, tocarry analytical information generated or measured at the test site to asuitable light receiving device. Analytical information transmitted byoptical means can be chemical or biological in nature. For example, theanalytical information can be used to identify a particular analyte,i.e., a component of interest, that is resident within the samplecontained at the test site and to determine the concentration of theanalyte. Examples of analytical signals include, among others, emission,absorption, scattering, refraction, and diffraction of electromagneticradiation over differing ranges of spectra. Many of these analyticalsignals are measured through spectroscopic techniques. Spectroscopygenerally involves irradiating a sample with some form ofelectromagnetic radiation (i.e., light), measuring an ensuingconsequence of the irradiation (e.g., absorption, emission, orscattering), and interpreting of the measured parameters to provide thedesired information. An example of an instrumental method ofspectroscopy entails the operation of a spectrophotometer, in which alight source in combination with the irradiated sample serves as theanalytical signal generator and the analytical signal is generated inthe form of an attenuated light beam. The attenuated signal is receivedby a suitable input transducer such as a photocell. The transducedsignal, such as electrical current, is then sent to a readout device.

As one example for implementing spectral analysis, a spectrophotometeruses ultraviolet (UV) and/or visible light, or in other cases infrared(IR) or near infrared (NIR) light, to scan the sample and calculateabsorbance values. In one specific method involving the UV or UV-visiblespectrophotometer, the UV sipper method, the sample is transferred to asample cell contained within the spectrophotometer, is scanned whileresiding in the sample cell, and preferably is then returned to the testvessel.

The determination of a property such as concentration of a given analytein a sample through a spectrochemical method typically involves severalsteps. These steps can include (1) acquiring an initial sample; (2)performing sample preparation and/or treatment to produce the analyticalsample; (3) using a sample introduction system to present the analyticalsample to the sample holding portion of a selected analytical instrument(e.g., transferring the sample to the sample-holding portion of a UVspectrophotometer); (4) measuring an analytical signal (e.g., an opticalsignal) derived from the analytical sample; (5) establishing acalibration function through the use of standards and calculations; (6)interpreting the analytical signal based on sample and referencemeasurements; and (7) feeding the interpreted signal to a readout and/orrecording system.

Conventional equipment employed in carrying out the above processes aregenerally known in various forms. Measurement of the analytical signalinvolves employing a suitable spectrochemical encoding system to encodethe chemical information associated with the sample, such asconcentration, in the form of an optical signal. In spectrochemicalsystems, the encoding process entails passing a beam of light throughthe sample under controlled conditions, in which case the desiredchemical information is encoded as the magnitude of optical signals atparticular wavelengths. Measurement and encoding can occur in or atsample cells, cuvettes, tanks, pipes, solid sample holders, or flowcells of various designs.

In addition, a suitable optical information selector is typically usedto sort out or discriminate the desired optical signal from the severalpotentially interfering signals produced by the encoding process. Forinstance, a wavelength selector can be used to discriminate on the basisof wavelength, or optical frequency. A radiation transducer orphotodetector is then activated to convert the optical signal into acorresponding electrical signal suitable for processing by theelectronic circuitry normally integrated into the analytical equipment.A readout device provides human-readable numerical data, the values ofwhich are proportional to the processed electrical signals.

For spectrophotometers operating according to UV-visible molecularabsorption methods, the quantity measured from a sample is the magnitudeof the radiant power or flux supplied from a radiation source that isabsorbed by the analyte species of the sample. Ideally, a value for theabsorbance A can be validly calculated from Beer's law:

${A = {{{- \log}\; T} = \;{{{- \log}\frac{P}{P_{0}}} = {abc}}}},$where T is the transmittance, P₀ is the magnitude of the radiant powerincident on the sample, P is the magnitude of the diminished (orattenuated) radiant power transmitted from the sample, a is theabsorptivity, b is the pathlength of absorption, and c is theconcentration of the absorbing species.

It thus can be seen that under suitable conditions, absorbance isdirectly proportional to analyte concentration through Beer's law. Theconcentration of the analyte can be determined from the absorbancevalue, which in turn is calculated from the ratio of measured radiationtransmitted and measured radiation incident. In addition, a trueabsorbance value can be obtained by measuring a reference or blank mediasample and taking the ratio of the radiant power transmitted through theanalyte sample to that transmitted through the blank sample.

In some types of conventional sample testing systems, samples aretransferred sequentially to one or more sample cells that are containedwithin the analytical instrument (e.g., spectrophotometer) itself.Samples are first taken from test vessels and, using sampling pumps,carried over sampling lines and through sampling filters. The samplesare then transported to a UV analyzer, an HPLC system, a fractioncollector, or the like. The analytical instrument may include a carouselthat holds several sample cuvettes, such that rotation of the carouselbrings each cuvette into position at the sample cell in a step-wisemanner. The pulsing of the light source supplying the initial opticalsignal can be synchronized by control means with the rotation of thecarousel.

Examples of UV-vis spectrophotometers are those available from Varian,Inc., Palo Alto, Calif., and designated as the CARY™ Series systems. Inparticular, the Varian CARY 50™ spectrophotometer includes a samplecompartment that contains a sample cell through which a light beam orpulse passes. Several sizes of sample cells are available. In addition,the spectrophotometer can be equipped with a multi-cell holder thataccommodates up to eighteen cells. A built-in movement mechanism movesthe cells past the light beam.

In other recently developed systems, fiber-optics are being used inconjunction with UV scans to conduct in-situ absorptionmeasurements—that is, measurements taken directly in the samplecontainers of either dissolution test equipment or sample analysisequipment. Fiber optic cables consist of, for example, glass fiberscoaxially surrounded by protective sheathing or cladding, and arecapable of carrying monochromatic light signals. A typical in-situfiber-optic method associated with dissolution testing involvessubmerging a dip-type fiber-optic UV probe in test media contained in avessel. A light beam (UV radiation) provided by a deuterium lamp isdirected through fiber-optic cabling to the probe. Within the probe, thelight travels through a quartz lens seated directly above a flowcell-type structure, the interior of which is filled with a quantity ofthe test media. The light passes through the test media in the flowcell, is reflected off a mirror positioned at the terminal end of theprobe, passes back through the flow cell and the quartz lens, andtravels through a second fiber-optic cable to a spectrometer.

For the previously described Varian CARY 50™ spectrophotometer, afiber-optic dip probe coupler is available to enable in-situ samplemeasurement methods and effectively replace the need for a sipperaccessory. This fiber optic coupler can be housed in thespectrophotometer unit in the place of the conventional sample cell. Thecoupler includes suitable connectors for coupling with the source andreturn optical fiber lines of a remote fiber-optic dip probe. The lightbeam from the light source of the spectrophotometer is directed to thesource line of the dip probe, and the resulting optical signaltransmitted back to the spectrophotmeter through the return line.

Fiber optics have also been employed in connection with sample-holdingcells. For example, U.S. Pat. No. 5,715,173 discloses an optical systemfor measuring transmitted light in which both a sample flow cell and areference flow cell are used. Light supplied from a light source istransmitted through an optical fiber to the sample flow cell, and alsothrough a second optical fiber to the reference flow cell. The path oftransmitted light from each flow cell is directed through respectiveoptical fibers toward an optical detector, and is controlled by anoptical path switcher in the form of a light selecting shutter or disk.

It is acknowledged by persons skilled in the art that, when working withan array of flow cells, sample cells, cuvettes, probes, and otherinstruments of optical measurement, and particularly in connection withfiber-optic components, there remains a need for efficiently andeffectively routing or distributing light energy to and from such samplecontainers. This need has been the subject of some developmentalefforts.

For instance, U.S. Pat. No. 5,526,451 discloses a fiber-optic sampleanalyzing system in which a plurality of cuvettes each have a sourceoptical fiber and a return optical fiber. A device is provided forselecting a source fiber to receive radiation for passage through aselected sample of one of the cuvettes, and for returning transmittedradiation from the selected cuvette through a selected return fiber to aspectrophotometer. The selection device includes a single rotatableretaining member supporting the respective ends of eight fiber-opticinput lines and eight corresponding fiber-optic output lines. Therespective ends of the fiber-optic lines are arranged in a ring aroundthe central axis of the retaining member. The eight input lines defineone half of the ring while the eight output lines define the other half.By this arrangement, each input line end affixed to the retaining memberhas a corresponding output line end affixed in diametrically oppositerelation along the ring. Rotation of the retaining member determineswhich pair of input and output lines are respectively aligned with aninput lens and an output lens disposed in spaced relation to theretaining member. A source beam passes through the input lens and intothe selected input line at the end supported by the retaining member.The source beam then travels through the input line and into the samplecuvette associated with that particular input line. From the samplecuvette, the transmitted beam travels through the output line associatedwith the selected input line and sample cuvette. This output lineterminates at its end supported by the retaining member. Since thisoutput end is aligned with the output lens spaced from the retainingmember, the transmitted beam passes through the output lens and isconducted to the analyzing means of the spectrophometer.

U.S. Pat. No. 5,112,134 discloses a vertical-beam photometricmeasurement system for performing enzyme-linked immunoabsorbent assay(ELISA) techniques. The system includes a light coupling andtransmission mechanism utilizing a cylindrical rotor and a fiber-opticdistributor. The mechanism receives light from a light assembly. Thecylindrical rotor includes an optical fiber having an input end locatedat its center and an output end located near the its periphery. As therotor rotates, the input end of the fiber of the rotor remainsstationary with respect to the light assembly, while the output endmoves around a circular path. The light output of the fiber of the rotoris received by a fiber optic distributor containing a multiplicity ofoptical fibers having their respective input ends arranged in a circulararray. As the rotor is indexed about its axis, the output end of itsfiber can be brought into alignment with successive fibers of thedistributor. On the output side of the distributor, the multiplicity offibers lead to a fiber manifold. The manifold aligns each fiber with acorresponding one of an array of assay sites. A detector board islocated below the assay sites. The detector board contains an array ofphotodetectors corresponding to the array of assay sites. Light from aselected fiber passes through a corresponding assay site, and into acorresponding photodetector of the detector board. As in other systems,this system requires a plurality of photedetectors and is not capable ofrouting the incident light from each sample well to a single detectionmeans.

U.S. Pat. No. 6,151,111 also discloses a vertical-beam photometricsystem in which a plate carrier sequentially advances an 8×12 microplatethrough a measurement station. Each column of eight wells is scanned bylight emitted from a bundle of eight corresponding distribution opticalfibers. Light supplied from a light source passes through amonochromator to a rotor assembly. Each of the eight distribution fibersenables light from the rotor assembly to be sequentially directed by acorresponding mirror vertically through a corresponding aperture, lens,and microplate well, and subsequently into a corresponding photodetectorlens. The rotor assembly consists of two mirrors positioned so as tobend light received by the rotor assembly 180 degrees, after which thelight can be directed into one of the distribution fibers. The rotor canthen be moved into alignment with another distribution fiber.

U.S. Pat. No. 4,989,932 discloses a multiplexer for enabling thesampling of a number of different samples. The multiplexer contains astationary cylindrical outer body and a rotatable optical barreldisposed within the outer body. A primary inlet port is located on oneside of the outer body through which light is introduced into themultiplexer. A primary exit port is located on an opposing side of theouter body through which light exits the multiplexer for transmission toan apparatus for optically analyzing a sample. Pairs of ancillary inletand exit ports are disposed around the cylindrical wall of the outerbody, and are oriented radially (or transversely) with respect to thelongitudinal axis. The rotatable barrel contains a first mirror and lensassociated with the ancillary exit ports, and a second mirror and lensassociated with the ancillary inlet ports. A stepper motor is used torotate the barrel to successively align the mirrors and lenses with aselected pair of ancillary inlet and exit ports. Light transmittedthrough the primary inlet port along the longitudinal axis of themultiplexer is turned at a right angle by the first mirror, passesthrough the first lens, and exits the multiplexer through the selectedancillary exit port. From the selected ancillary exit port, the light istransmitted through a fiber-optic bundle to a sample and returns to themultiplexer through the corresponding selected ancillary inlet port.From the selected ancillary inlet port, the light passes through thesecond lens, is turned at a right angle by the second mirror, and exitsthe multiplexer along the longitudinal axis. Other pairs of ancillaryinlet and exit ports can be selected by rotating the barrel. In anotherembodiment disclosed in this patent, incoming light is received by anoptical rod that has an angled mirrored surface at its end. Rotation ofthe rod by a stepper motor positions the angled mirrored surface todirect the light into a selected fiber-optic bundle.

U.S. Pat. No. 5,804,453 discloses a system in which a fiber-opticbiosensor probe is inserted into a test tube. The probe receives a lightbeam from a light source and sends a testing signal to thephotodetectors of a spectrometer. Time division multiplexing anddemultiplexing are implemented to distribute light to and from severalbiosensors. Switching among inputs and outputs is controlled by an inputcontrol signal provided by an electronic clocked counter.

U.S. Pat. No. 5,580,784 discloses a system in which a plurality ofchemical sensors are associated with several sample vials and arrangedbetween a light source and a photodetector. Optical fibers are used todirect radiation into each sensor, as well as to direct emissions outfrom the sensors. A wavelength-tunable filter is combined with anoptical multiplexer to direct radiation serially to each sensor throughthe fibers.

In view of the current state of the art, there is a continuing need forimproved means for efficiently and effectively routing or distributinglight energy to and from sample testing sites. It would be therefore beadvantageous to provide a fiber-optic channel selection apparatus thatutilizes mechanical components to effect indexing among several opticalinput and/or output channels in an efficient and controlled mannerwithout the need for costly optics-based switching components. Inparticular, it would be advantagous to provide an apparatus that enablesanalysis of multiple samples using only a single light source and asingle detection means. Such an apparatus should be designed to minimizelight loss and be compatible with a wide range of optical-basedmeasurement systems. The present invention is provided to address theseand other problems associated with the prior art.

SUMMARY OF THE INVENTION

The present invention provides a mechanical, rotary optical multiplexer(and/or demultiplexer) apparatus for selecting channels through which abeam or pulse of light is routed in an indexing manner. The apparatuscan comprise one, two, or more rotary indexing devices. One of therotary indexing devices demultiplexes a beam of light by distributingthe light from a single, common outgoing or source line into a selectedone of a plurality of outgoing or source channels. The selection isaccomplished by rotating the demultiplexing device into a position atwhich the common outgoing or source line can optically communicate withthe selected outgoing channel. The other rotary indexing device, whenemployed in certain embodiments of the invention, multiplexes a beam oflight for transmission into a single incoming or return line byselecting one of a plurality of incoming or return channels. Theselection is accomplished by rotating the multiplexing device into aposition at which the common incoming or return line can opticallycommunicate with the selected incoming or return channel. In otherembodiments, each incoming or return line is optically aligned with asignal receiving means such as a photodetector, thereby eliminating theneed for the second rotary indexing device and the common incoming orreturn line.

When two such rotary devices are provided in this manner, they aremechanically interfaced in a preferred embodiment so that rotation ofone device concurs with rotation of the other device, with the resultthat the selection of a certain channel of the one device concurs withthe selection of a corresponding channel of the other device. Forinstance, if each device includes twelve channels and thus twelve indexpositions, the selection of the channel at index position 1 of the onedevice simultaneously results in the selection of the channel at indexposition 1 of the other device.

According to one embodiment of the invention, each rotary devicecomprises two fixed components (i.e., first and second fixedcomponents), a rotary component, and one or more bearings providing aninterface between the fixed components and the rotary component. Therotary component is interposed between the two fixed components. Eachfixed component faces a respective end of the rotary component. One ofthe fixed components (e.g., the first fixed component) has an opticalaperture at its axial center. The other fixed component (e.g., thesecond fixed component) has a plurality of optical apertures oriented ina circular arrangement about its axial center. The number of opticalapertures in the circular arrangement corresponds to the number ofoptical channels selectable by the apparatus of the invention. Therotary component has a light guiding path such as an optical fiberhaving one end located at the axial center of the rotary component andanother end located radially outward with respect to the axial center.The centrally located end of the optical fiber of the rotary componentis separated from the centrally located optical aperture of the firstfixed component by a very small air gap. The offset end of the opticalfiber of the rotary component is likewise separated from the pluralityof optical apertures of the second fixed component by a very small airgap. These air gaps optimize light transmission while minimizing lightloss, and avoid the necessity of using expensive additional opticalcomponents to couple the respective apertures and fiber ends of thefixed and rotary components. Indexed rotation of the rotary componentwith respect to the second fixed component results in selective couplingbetween the offset end of the optical fiber of the rotary component andeach aperture of the second fixed component.

As indicated previously, the two rotary devices included with theapparatus according to at least one embodiment rotate together through amechanical interface. This interface can be accomplished through asuitable set of gears arranged such that rotation of at least one gearresults in rotation of both rotary devices. For example, each rotarydevice could be provided with its own gear, and each of these gearscould be placed in meshing engagement with a third gear. While manualrotation of the third gear in order to rotate the other gears ispossible, it is preferred that the third gear be powered throughconnection to a motor or similarly automated device. The motor couldthen be electronically controlled by suitable electronic hardware and/orsoftware. As an alternative to providing gears with each rotary device,gear-like teeth could be formed on respective structures of the rotarydevices to eliminate additional gearing. In either case, the rotarydevices of the apparatus can be rotated continuously without the need toreverse rotation upon completion of the indexing of each channelprovided. For instance, for a twelve-channel apparatus, the samplinginterval from index position 1 to index position 2 is equivalent to thesampling interval from index position 12 to index position 1.

In an alternative embodiment of the invention, the first rotary deviceutilized to select an outgoing channel is provided, but the secondrotary device utilized to select an incoming channel is eliminated infavor of suitably collecting a bundle of optical return fibersconstituting the incoming channels. The bundle of optical return fibersis disposed at a fixed position at which the ends of the fibers areoptically aligned with the receiving window of a optical detectiondevice.

The invention as just described offers advantages when incorporated intoany system that includes one or more light sources and one or moredevices adapted for receiving light energy from the light sources. Insuch systems, the mechanical multiplexing/demultiplexing functionsrealized by the present invention are useful in networking one or morelight signals from selected light sources to selected receiver devices.The invention also offers advantages when incorporated into any systemthat uses optics to route optical signals over several lines or channelsbetween a single light source and a single detector. An example of thislatter system is a UV-vis spectrophotometer, which is generally designedto conduct UV scans on prepared samples. It is often desirable to scan amultitude of samples. In accordance with the present invention, eachsample can be held in a test vessel or a suitable cell or well, or inany other suitable sample holding or containment means, and fiber-opticinput and output lines can be brought into operative communication witheach sample test site, or with each probe associated with the sampletest site. In this manner, each cell, probe, vessel or test siterespectively becomes associated with one of the channels of theapparatus of the invention, and hence becomes associated with thecorresponding index positions of the rotary device or devices of theapparatus. Accordingly, the selection of index position 1 of each rotarydevice, for example, corresponds to the selection of test vessel 1, cell1, and so on.

According to another embodiment of the present invention, an apparatusfor selectively coupling fiber optic lines comprises an optical inputselection device, an optical output selection device, and a rotatablecoupling mechanism interconnecting the optical input selection deviceand the optical output selection device. The optical input selectiondevice is rotatable about a first central axis, and comprises a firstinput end and a first output end. The first input end is disposedcollinearly with the first central axis, and the first output end isdisposed at a radially offset distance from the first central axis. Theoptical output selection device is rotatable about a second centralaxis, and comprises a second input end and a second output end. Thesecond input end is disposed at a radially offset distance from thesecond central axis, and the second output end is disposed collinearlywith the second central axis. Rotation of the coupling mechanism causesrotation of the first output end and the second input end.

The apparatus advantageously further comprises a plurality offiber-optic source lines and a plurality of fiber-optic return lines.The plurality of source lines have respective source line input endsfixedly disposed in a circular arrangement, and the plurality of returnlines have respective return line output ends fixedly disposed in acircular arrangement. Each source line input end is selectivelyoptically alignable with the first output end of the optical inputselection device through incremental rotation of the optical inputselection device. Each return line output end is selectively opticallyalignable with the second input end of the optical output selectiondevice through incremental rotation of the optical output selectiondevice.

The optical input selection device and optical output selection devicecan be structured with rotary and stationary elements as describedhereinabove.

In a specific implementation of this embodiment, the optical inputselection device provides an optical path between the first input endand the first output end. In addition, the optical output selectiondevice provides an optical path between the second input end and thesecond output end. Preferably, the optical paths are provided by firstand second internal optical fibers, respectively.

The interconnection of the optical input and output selection devices bythe coupling mechanism is advantageously effected by the provision ofgearing and/or endless members as described herein. As a result, eachrotational index position of the optical input selection device isassociated with a corresponding rotational index position of the opticaloutput selection device. Depending on the particular design orconstruction of the coupling mechanism and its associated components,rotation of the coupling mechanism or a component thereof will result inrotation of both the optical input and output selection devices ineither the same rotational direction or in the reverse direction.

According to a further embodiment of the present invention, an apparatusfor routing optical signals comprises a base, an optical channelselection device supported by the base, a mounting member supported bythe base, and a plurality of fiber-optic return lines. The opticalchannel selection device is rotatable about a central axis, andcomprises an internal optical fiber having an internal optical fiberinput end and an internal optical fiber output end. The internal opticalfiber input end is disposed collinearly with the central axis, and theinternal optical fiber output end disposed at a radially offset distancefrom the central axis. Each return line has a return line output endfixedly supported by the mounting member.

Preferably, the apparatus also comprises a plurality of fiber-opticsource lines having respective source line input ends fixedly disposedin a circular arrangement. Each source line input end is selectivelyoptically alignable with the internal optical fiber output end of theoptical channel selection device through incremental rotation of theoptical channel selection device.

Preferably, the optical channel selection device comprises a rotaryelement and a stationary element. The rotary element is rotatable aboutthe central axis, and comprises an input end surface and an opposingoutput end surface. The internal optical fiber input end is exposed atthe input end surface and the internal optical fiber output end isexposed at the output end surface. The first stationary element isdisposed adjacent to the output end surface, and has a plurality ofcircumferentially spaced first stationary element apertures. Each firststationary element aperture is disposed at the radially offset distancefrom the central axis, and the internal optical fiber output end isalignable with a selected one of the first stationary element aperturesthrough rotation of the rotary element.

The apparatus can also comprise a light source communicating with theinternal optical fiber input end, and an optical receiving devicealigned with each return line output end. In addition, the apparatus caninterface with a plurality of sample test sites. Each sample test siteoptically communicates with the internal optical fiber end of theoptical channel selection device at a selected rotary index positionthereof and one of the optical return lines corresponding to theselected rotary index position.

According to another implementation, an apparatus for selectivelycoupling fiber optic lines comprises an optical input selection devicerotatable about a first axis, an optical output selection devicerotatable about a second axis, and a rotatable coupling mechanisminterconnecting the optical input selection device and the opticaloutput selection device. The optical input selection device includes afirst rotary element having a first internal bore and a first internaloptical fiber extending through the first internal bore. The opticaloutput selection device includes a second rotary element having a secondinternal bore and a second internal optical fiber extending through thesecond internal bore.

The fiber-optic channel selecting apparatus according to any ofembodiments described herein can be directly integrated into the designof an optical-based sample measurement and/or analysis system orinstrument, such as a spectroscopic apparatus. An example of aspectroscopic apparatus is a spectrophotometer.

According to a method for selecting an optical channel from a pluralityof optical channels, an optical channel selecting device is provided.The optical channel selecting device comprises a rotary member includingan input side, an output side, and an internal optical path runningbetween the input side and the output side. The rotary member is rotatedto a position corresponding to a selected optical channel. At thisposition, the internal optical path can optically communicate with acorresponding one of a plurality of optical source lines and acorresponding one of a plurality of optical return lines separate fromthe optical source lines.

According to another method of the present invention, an optical channelis selected from a plurality of optical channels. An optical channelselecting apparatus is provided that comprises an input selection deviceincluding a first input end and a first output end, an output selectiondevice including a second input end and a second output end, and acoupling mechanism interconnecting the input selection device and theoutput selection device. The input selection device provides an inputpath between the first input end and the first output end, and theoutput selection device provides an output path between the second inputend and the second output end. The optical channel selecting apparatusselects a first channel by causing the coupling mechanism to move thefirst output end to a first input position and the second input end to afirst output position. Other channels can be selected by causing thecoupling mechanism to move the first output end and the second input endto other input and output positions corresponding to other availablechannels.

According to another method of the present invention for selecting anoptical channel from a plurality of optical channels, an input selectiondevice is provided that comprises an input end, an output end, and aninput path defined between the input end and the output end. A pluralityof optical return fibers are provided that have respective fiber endsdisposed at a distance from an optical receiving device. A first channelis selected by causing the input selection device to rotate the outputend to a first position at which the input path is optically coupledwith a respective return fiber. Other channels are selected throughfurther rotation of the output end to positions corresponding to otherreturn fibers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fiber-optic channel selectionapparatus provided in accordance with the present invention;

FIG. 2 is a side elevation view of the apparatus illustrated in FIG. 1;

FIG. 3 is a top plan view of the apparatus illustrated in FIG. 1;

FIG. 4 is a rear elevation view of the apparatus illustrated in FIG. 1showing the interconnection of rotary devices provided in accordancewith one embodiment of the present invention;

FIG. 5A is a cross-sectional view of a rotary device for distributing alight beam or signal from a single input to one or more fiber-opticchannels in accordance with the present invention;

FIG. 5B is a cross-sectional view of a rotary device for distributinglight beams or signals from one or more fiber-optic channels to a singleoutput in accordance with the present invention;

FIG. 6A is a cross-sectional view of an optical input selection deviceprovided with the apparatus illustrated in FIGS. 1–4, including therotary device illustrated in FIG. 5A;

FIG. 6B is cross-sectional view of an optical output selection deviceprovided with the apparatus illustrated in FIGS. 1–4, including therotary device illustrated in FIG. 5B;

FIG. 7A is a plan view illustrating either the input side of the opticalinput selection device illustrated in FIG. 6A or the output side of theoptical output selection device illustrated in FIG. 6B;

FIG. 7B is a plan view illustrating either the output side of theoptical input selection device illustrated in FIG. 6A or the input sideof the optical output selection device illustrated in FIG. 6B;

FIG. 7C is a perspective view of either of the optical input selectiondevice illustrated in FIG. 6A or the optical output selection deviceillustrated in FIG. 6B;

FIG. 8 is a schematic diagram of an analytical testing and dataacquisition system in which the apparatus or portions thereofillustrated in FIGS. 1–7C is incorporated in accordance with the presentinvention;

FIG. 9 is a schematic diagram of another analytical testing and dataacquisition system in which the apparatus or portions thereofillustrated in FIGS. 1–7C is incorporated;

FIG. 10A is a front elevation view of a fiber-optic bundle mountingcomponent provided with the system illustrated in FIG. 9; and

FIG. 10B is a cross-sectional side view of the mounting componentillustrated in FIG. 10A.

DETAILED DESCRIPTION OF THE INVENTION

In general, the term “communicate” (e.g., a first component“communicates with” or “is in communication with” a second component) isused herein to indicate a structural, functional, mechanical, optical,or fluidic relationship between two or more components or elements. Assuch, the fact that one component is said to communicate with a secondcomponent is not intended to exclude the possibility that additionalcomponents may be present between, and/or operatively associated orengaged with, the first and second components.

As used herein, the term “multiplexer” is broadly defined to indicate asystem or device that includes a plurality of independent, individualinput lines or channels and a single output line or channel (i.e., acommon path or bus). One of the input lines can be selected so that itsvalue or signal is transmitted or routed over the output line. Thus, themultiplexer could also be referred to as a data selector. In addition,the term “demultiplexer” is broadly defined herein as implementing theconverse function of the multiplexer. That is, a demultiplexer is asystem or device that includes one input line or channel (i.e., a commonpath or bus) and a plurality of output lines or channels. One of theoutput lines is selected to receive the value or signal provided by theinput line. Thus, the demultiplexer could also be referred to as a datadistributor. These terms, as used herein, are therefore intended to havea broader meaning than, for instance, the meanings typically understoodby persons associated with the communications or electronics industries,wherein the terms are often restricted to meaning a system in which allelements of a given signal are observed simultaneously. For convenience,the term “multiplexer” or “multiplexing apparatus” as used hereinafteris intended to cover a device or system that includes a multiplexerand/or a demultiplexer.

As used herein, the terms “beam,” “pulse,” and “optical signal” areintended to be interchangeable to indicate that the present invention isapplicable to the transmission of light energy by both continuous andnon-continuous methods.

As used herein, the terms “aperture” and “bore” are used interchangeablyto denote any opening through which light energy can be transmitted withan acceptable degree of efficiency and an acceptable minimum of lightloss. Such an opening can include an optical fiber for these purposes aswell. Whether the term “aperture” or “bore” is more appropriate could,for instance, depend on the thickness of the structural body throughwhich the opening runs, but in any case the two terms are consideredherein to be interchangeable.

Referring now to FIGS. 1–4, an optical signal multiplexing apparatus,generally designated 10, is illustrated in accordance with the presentinvention. Multiplexing apparatus 10 comprises an enclosure 12 mountedto a base 14. Two rows of apertures (see FIG. 3), generally designated16 and 18, respectively, are formed on a top surface 12A of enclosure12. Two corresponding rows of fiber optic cable ferrules or fittingsgenerally designated 21 and 23, respectively, (see FIG. 1) are mountedin these apertures 16 and 18. Individual fiber-optic source linesOSL₁–OSL_(n) (where, in the illustrated exemplary embodiment, n=8)extend through the respective fittings of row 23 (and apertures 18), andindividual fiber-optic return lines ORL₁–ORL_(n) extend through therespective fittings of the other row 21 (and apertures 16). In FIGS. 1and 3, only the first pair of optical source and return lines, opticalsource line OSL₁ and optical return line ORL_(l), are shown. In FIG. 2,the respective bundles of optical source lines OSL₁–OSL_(n) and opticalreturn lines ORL₁–ORL_(n) are schematically depicted by large arrows toindicate generally the direction of optical signals into and out frommultiplexing apparatus 10.

Portions of enclosure 12 are removed in FIGS. 1–4 to illustrate theinterior components disposed within enclosure 12. The primary operativeinterior components are two rotary indexing devices. One rotary deviceis referred to herein as an optical source line selector device,generally designated 80, and the other rotary device is referred to asan optical return line selector device, generally designated 130.

Source and return line selector devices 80 and 130 are situated adjacentto one another and are supported in fixed relation to each other, forexample, by two axially spaced mounting blocks 26 and 28 that extendupwardly from base 14. A ferrule or input fitting 31 is connected to aninput end of source line selector device 80. A circular array offittings, generally designated 33, are connected to an output end ofsource line selector device 80. Another circular array of fittings,generally designated 35, are connected to an input end of return lineselector device 130. A ferrule or output fitting 37 is connected to anoutput end of return line selector device 130. A common source line orinput bus IB is connected to input fitting 31, and a common return lineor output bus OB is connected to output fitting 37. As just described,each individual fiber-optic source line OSL₁–OSL_(n) runs through acorresponding fitting 23 of aperture row 18, and each individual returnline ORL₁–ORL_(n) runs through fittings 21 mounted to aperture row 16.Although not specifically shown in FIG. 1 for clarity, each individualfiber optic source line OSL₁–OSL_(n) is connected to a corresponding oneof fittings 33 of source line selector device 80, and each individualreturn line ORL₁–ORL_(n) is likewise connected to a corresponding one offittings 35 of return line selector device 130. As described more fullybelow, source line selector device 80 functions to select which one ofthe fiber-optic source lines OSL₁–OSL_(n) is optically coupled to inputbus IB over a given interval of time. Return line selector device 130functions to select which one of the fiber-optic return linesORL₁–ORL_(n) is optically coupled to output bus OB over the sameinterval of time.

As best shown in FIGS. 3 and 4, multiplexing apparatus 10 furthercomprises a means for causing both source line selector device 80 andreturn line selector device 130 to rotate simultaneously and in anindexing fashion. Preferably, the means is provided in the form of apowered mechanism adapted to transfer rotational force through a forcetransmission mechanism. In the exemplary embodiment illustrated in FIGS.1–4, the powered mechanism is a motor 40 (such as, for example, a DCstepper motor) that causes a shaft 42 to rotate through programmedincrements. The transmission mechanism includes an arrangement of gearwheels 45, 47 and 49. Gear wheel 45 is mounted to shaft 42 and thusrotates about the axis of shaft 42.

Gear wheel 47 is mounted to source line selector device 80 and rotatesabout an axis L, of source line selector device 80 (see FIG. 4). Gearwheel 49 is mounted to return line selector device 130 and rotates aboutan axis L₂ of return line selector device 130. Gear wheels 47 and 49 aredisposed in meshing engagement with gear wheel 45. Accordingly,clockwise rotation of gear wheel 45 results in counterclockwise rotationof both gear wheels 47 and 49. Conversely, counterclockwise rotation ofgear wheel 45 results in clockwise rotation of both gear wheels 47 and49. Moreover, gear wheels 47 and 49 are similarly sized and have thesame number of teeth.

As a result, rotation of gear wheel 45 through a given incremental arclength causes rotation of both gear wheels 47 and 49 through anotherproportional incremental arc length. The arc length through which gearwheel 47 rotates is the same as the arc length through which gear wheel49 rotates.

As appreciated by persons skilled in the art, multiplexing apparatus 10can be provided with means for verifying the positions of the variousrotating components. For example, primary position verification can beeffected by providing an optical encoder (not shown) that is focused onshaft 42 of motor 40. As a secondary mode of position verification, Halleffect sensors (not shown) can be provided to interface with a magnet(not shown) mounted on each gear wheel 47 and 49 respectively associatedwith source line selector device 80 and return line selector device 130.With respect to each source line selector device 80 and return lineselector device 130, each corresponding set of Hall effect sensors wouldbe mounted at each index position, such as by mounting the sensors in acircular array on a separate disks that rotates with correspondingbarrel 85 or 135 in parallel with the magnet mounted to correspondinggear wheel 47 or 49.

Referring now to FIGS. 5A–7C, details of source line selector device 80and return line selector device 130 are illustrated. Referringspecifically to FIG. 5A, source line selector device 80 comprises arotary element or barrel 85 that is rotatable about its central axis L₁.Barrel 85 includes an outer lateral surface 85A, an input end surface85B, and an output end surface 85C. Gear wheel 47 is fitted around theperiphery of outer lateral surface 85A. Gear wheel 47 is either aseparate component or comprises teeth formed around barrel 85. Aninternal bore 87 extends through the body of barrel 85, and has an inputbore end 87A opening at input end surface 85B and an output bore end 87Bopening at output end surface 85C. Input bore end 87A is coincident withaxis L_(l), and thus the position of input bore end 87A in relation toaxis L₁ does not change during rotation of barrel 85. Output bore end87B, on the other hand, is disposed at a location on output end surface85C that is offset from axis L₁ by a radial offset distance equal toradius R. Rotation of barrel 85 about axis L₁ therefore results inrotation of output bore end 87B along a circular path of radius R, asdefined on output end surface 85C with respect to axis L₁. An internaloptical fiber 90 (see FIG. 6A) extends throughout internal bore 87.Internal optical fiber 90 terminates at an input fiber end 90A (see FIG.6A) located at input bore end 87A, and terminates at an output fiber end90B (see FIG. 6A) located at output bore end 87B. Thus, input fiber end90A is coincident with axis L₁ and output fiber end 90B is offset fromaxis L₁ by radial offset distance (or radius) R. Rotation of barrel 85about axis L₁ does not affect the position of input fiber end 90A, butresults in a circumferential change in the position of output fiber end90B with respect to axis L₁.

Referring to FIG. 6A, source line selector device 80 is designed topermit rotational indexing of barrel 85 about axis L₁. Through thisrotational movement, output fiber end 90B can be selectively positionedat one of a plurality of equally spaced index locations around acircumference on output end surface 85C. This circumference is swept outby the conceptual end point of radius R in relation to axis L₁. In orderto implement source fiber “channel” or line selection, barrel 85 rotateswith respect to some type of stationary member that includes a number offixed-position optical reception points corresponding to the pluralityof index locations. In FIG. 6A, for example, the channel selection isimplemented according to the invention by providing a stationary opticalreception member. In the present embodiment, the stationary opticalreception member is a bearing sleeve or cap 95 disposed at the outputside of barrel 85. A bearing 105 provides an interface between rotatablebarrel 85 and stationary bearing sleeve 95. As illustrated in FIG. 6A,bearing 105 can be a roller bearing of conventional design that includesan inner ring 105A, an outer ring 105B, and a series of balls 107contacting the respective, opposing raceways of inner ring 105A andouter ring 105B. As understood by persons skilled in the art, balls 107typically are interposed between inner ring 105A and outer ring 105B andin a circumferentially spaced arrangement through the use of a retainingelement (not shown) forming some type of frame, cage, or carriage aroundeach ball 107. Inner ring 105A firmly contacts (such as by pressfitting) lateral outer surface 85A of barrel 85, while outer ring 105Bfirmly contacts at least the inner surface of an annular section 95A ofbearing sleeve 95. By this arrangement, inner ring 105A rotates withbarrel 85 while outer ring 105B remains in a fixed position withstationary bearing sleeve 95. It will be understood that bearing 105could be either a ball bearing or a needle bearing, or some other typeof bearing that permits barrel 85 to rotate in a stable manner withrespect to bearing sleeve 95. That is, rotatable needle elements couldbe substituted for balls 107 illustrated in FIG. 6A.

In addition to its annular section 95A, bearing sleeve 95 includes aplate section 95B transversely oriented with respect to axis L₁ ofsource line selector device 80. Plate section 95B is immediatelyadjacent to output end surface 85C of barrel 85. Plate section 95Bincludes a plurality of apertures 97 (only two of which are shown inFIG. 6A) arranged in a circular array of radius R with respect to axisL₁. These apertures 97 constitute the previously describedfixed-position optical reception points. The actual number of apertures97 corresponds to the number of indices at which output fiber end 90B ofinternal optical fiber 90 can be selectively positioned, and accordinglycorresponds to the number of individual optical channels or lines intowhich an optical signal traveling through internal optical fiber 90 frominput fiber end 90A can be selectively directed through output fiber end90B. The specific number of apertures 97 (and hence the specific numberof individual optical channels and index positions) will depend on thenumber of test sites to which optical source signals are to be sent.Besides the test sites that contain analytical samples, one or more ofthese test sites could hold reference or control samples (e.g., sourcesfor obtaining blank or standard measurement data). In the example shownin FIG. 7B, plate section 95B of bearing sleeve 95 includes an array ofeight apertures 97 to handle eight separate optical channels or lines.It will be understood, however, that more or less apertures 97 could beprovided, again depending on the number of separate optical channels.

The specific provision of bearing 105 and bearing sleeve 95, in thearrangement and design illustrated in FIG. 6A, ensures that any lightloss from the light conducting components of source line selector device80 is negligible. The size of the air gap between output end surface 85Cof barrel 85 and plate section 95B of bearing sleeve 95 is preset toprovide optimal light transmission. Annular section 95A and platesection 95B of bearing sleeve 95 cooperatively form a shoulder aroundbearing 105 and output end surface 85C to prevent light losses. Infurtherance of the purpose of preventing light loss in this particulararrangement, it is preferable that the axial edges of inner ring 105Aand outer ring 105B of bearing 105 facing plate section 95B of bearingsleeve 95 be substantially flush with output end surface 85C of barrel85.

Although source line selector device 80 and its barrel 85 are notexpected to encounter axial thrust forces during the operation ofmultiplexing device 10, source line selector device 80 can furtherinclude a second bearing 125 and corresponding bearing sleeve 115mounted at the input side, as also shown in FIG. 6A. The design andarrangement of input-side bearing 125 and bearing sleeve 115 can besimilar to those of output-side bearing 105 and bearing sleeve 95.Input-side bearing sleeve 115 thus includes an annular section 115A anda plate section 115B. As one principal difference, however, input-sidebearing sleeve 115 includes only one aperture 117 formed in its platesection 115B (see also FIG. 7A). This single aperture 117 is situatedcoincident with axis L₁ and is immediately adjacent to input fiber end90A of internal optical fiber 90. The inclusion of input-side bearing125 and bearing sleeve 115 lends stability to the indexing movements ofbarrel 85 and overall operation of source line selector device 80, andfurther facilitates the optical coupling of internal optical fiber 90 toinput bus IB (see FIG. 1). Input-side bearing 125 can comprise balls 127interposed between an inner ring 125A and an outer ring 125B.

Referring to FIG. 5B, return line selector device 130 comprises featuressimilar to those of source line selector device 80 although, as shown inFIG. 1, the axial positions of the input and output sides of return lineselector device 130 are reversed in comparison to those of source lineselector device 80. Specifically, return line selector device 130comprises a rotary element or barrel 135 rotatable about its centralaxis L₂. Barrel 135 includes an outer lateral surface 135A, an input endsurface 135B, and an output end surface 135C. Gear wheel 49 is fittedaround the periphery of outer lateral surface 135A. Gear wheel 49 iseither a separate component or comprises teeth formed around barrel 135.An internal bore 137 extends through the body of barrel 135, and has aninput bore end 137A opening at input end surface 135B and an output boreend 137B opening at output end surface 135C. Input bore end 137A isdisposed at a location on input end surface 135B that is offset fromaxis L₂ by a radial offset distance equal to radius R. Rotation ofbarrel 135 about axis L₂ therefore results in rotation of input bore end137A along a circular path of radius R defined on input end surface 135Bwith respect to axis L₂. Output bore end 137B, on the other hand, iscoincident with axis L₂ such that its position in relation to axis L₂does not change during rotation of barrel 135. An internal optical fiber140 extends throughout internal bore 137. Internal optical fiber 140(see FIG. 6B) terminates at an input fiber end 140A located at inputbore end 137A, and terminates at an output fiber end 140B located atoutput bore end 137B. Thus, input fiber end 140A is offset from axis L₂by radial offset distance (or radius) R and output fiber end 140B iscoincident with axis L₂. Rotation of barrel 135 about axis L₂ does notaffect the position of output fiber end 140B, but results in acircumferential change in the position of input fiber end 140A withrespect to axis L₂.

Referring to FIG. 6B, return line selector device 130 enables rotationalindexing of barrel 135 about axis L₂ in a manner analogous to sourceline selector device 80. Through the rotational movement effected byreturn line selector device 130, its input fiber end 140A can beselectively positioned at one of a plurality of equally spaced indexlocations around a circumference of radius R defined on input endsurface 135B. In order to implement return fiber “channel” or lineselection, return line selector device 130 includes a stationary bearingsleeve 145 disposed at the output side of barrel 135. As in the case ofsource fiber selector device 80, barrel 135 rotates with respect tobearing sleeve 145. A bearing 155 provides an interface betweenrotatable barrel 135 and stationary bearing sleeve 145. Bearing 155 canbe provided in the form of a roller bearing that includes an inner ring155A, an outer ring 155B, and a series of balls 157 or needles accordingto conventional designs. Inner ring 155A rotates with barrel 135 whileouter ring 155B remains in a fixed position with stationary bearingsleeve 145.

Bearing sleeve 145 of return line selector device 130 comprises anannular section 145A coaxially disposed around bearing 155 and a platesection 145B transversely oriented with respect to axis L₂ of returnline selector device 130. Plate section 145B is immediately adjacent toinput end surface 135B of barrel 135 with an air gap therebetween, whichis dimensioned for optimal optical transmission. Annular section 145Aand plate section 145B of bearing sleeve 145 cooperatively form ashoulder around bearing 155 and input end surface 135B. This arrangementof bearing 155 and bearing sleeve 145 ensures that any light loss fromthe light conducting components of return line selector device 130 isnegligible. In furtherance of the purpose of preventing light loss inthis particular arrangement, it is preferable that the axial edges ofinner ring 155A and outer ring 155B of bearing 155 facing plate section145B of bearing sleeve 145 be substantially flush with input end surface135B of barrel 135. Plate section 145B includes a plurality of apertures147 (only two of which are shown in FIG. 6B) arranged in a circulararray of radius R with respect to axis L₂. These apertures 147constitute fixed-position optical coupling points between the individualreturn fibers ORL₁–ORL_(n) and input fiber end 140A of internal opticalfiber 140. The actual number of apertures 147 corresponds to the numberof indices at which input fiber end 140A can be selectively positioned,and accordingly corresponds to the number of individual optical channelsor lines from which an optical signal can be selectively directed intoinput fiber end 140A. The specific number of apertures 147 (and hencethe specific number of individual optical channels and index positions)will depend on the number of sites or detection areas from which opticalreturn signals are to be received.

As also shown in FIG. 6B, return line selector device 130 can furtherinclude a second bearing 175 and corresponding bearing sleeve 165mounted at the output side. The design and arrangement of output-sidebearing 175 and bearing sleeve 165 can be similar to those of input-sidebearing 105 and bearing sleeve 95. Output-side bearing sleeve 165 thusincludes an annular section 165A and a plate section 165B. Output-sidebearing sleeve 165, however, includes only one aperture 167 formed inits plate section 165B. This single aperture 167 is situated coincidentwith axis L₂ and is immediately adjacent to output fiber end 140B ofinternal optical fiber 140 and, on the other side, to output bus OB (seeFIG. 1). Output-side bearing 175 can comprise balls 177 interposedbetween an inner ring 175A and an outer ring 175B.

FIG. 7A illustrates plate section 115B and single aperture 117 ofinput-side bearing sleeve 115 of source line selector device 80. FIG. 7Billustrates plate section 95B and multiple apertures 97 of output-sidebearing sleeve 95 of source line selector device 80. FIG. 7C 20illustrates input-side bearing sleeve 115, output-side bearing sleeve95, and bearings 105 and 125 assembled onto barrel 85 of source lineselector device 80. It will be understood that FIGS. 7A-7C are likewiserepresentative of the structure of return line selector device 130, butwith the input and output sides reversed. That is, FIG. 7A couldrepresent plate section 165B and single aperture 167 of output-sidebearing sleeve 165 of return line selector device 130, and FIG. 7B couldrepresent plate section 145B and multiple apertures 147 of input-sidebearing sleeve 145 of return line selector device 130. Likewise, FIG. 7Ccan be considered as illustrating input-side bearing sleeve 145,output-side bearing sleeve 165, and bearings 155 and 175 assembled ontobarrel 135 of return line selector device 130.

According to another aspect of the invention, FIG. 8 illustrates thegeneral features of an analytical testing and data acquisition system,generally designated 200, in which multiplexer apparatus 10 canadvantageously operate. In addition to multiplexer apparatus 10,analytical testing system 200 comprises a light source, generallydesignated 210, a data encoding or analytical signal generating systemor arrangement, generally designated 220, and an optical signalreceiving device or system generally designated 230.

Light source 210 can be any type of suitable continuous ornon-continuous optical source. Non-limiting examples include deuteriumarc lamps, xenon arc lamps, quartz halogen filament lamps, and tungstenfilament lamps. In one specific example, a pulsed light source such as axenon flash lamp could be employed to emit very short, intense bursts oflight. This type of lamp flashes only when acquiring a data point, ascompared to a diode array that exposes the sample to the entirewavelength range with each reading and potentially causes degradation ofphotosensitive samples. As described in commonly assigned U.S. Pat. No.6,002,477, because it emits light on a non-continuous basis, the xenonflash lamp does not require a mechanical means such as a chopper forinterrupting the light beam during measurement of a dark signal.

One specific example of a xenon flash lamp that is capable of acquiringeighty data points per second is employed in CARY™ Seriesspectrophotometers commercially available from Varian, Inc, Palo Alto,Calif.

Data encoding or analytical signal generating system 220 can compriseany device or system adapted to contain and expose one or more samplesto the light energy supplied by light source in order to encodeinformation about that sample as the light passes through the sample andthe sample is irradiated. For example, data encoding system couldconstitute an array of test sites F₁–F_(n) such as sample measurementand/or holding sites. These test sites F₁–F_(n) can be defined by avariety of sample measurement/containment components, such as solidsample holders, sample containers or cells, test vessels, flow cells,tanks, pipes, the wells of a quartz microtitre plate or similarmicrocells capable of transmitting light, and specially designedfiber-optic probes.

Signal receiving device or system 230 could be any type of instrument orsystem of instruments adapted to receive and process the optical signalssupplied by data encoding device 220. The specific property of thesample substance to be analyzed will dictate the type of equipment orinstrumentation used to analyze samples taken from, for example, testvessels. Moreover, the various components comprising signal receivingdevice 230 will depend on the type of analytical signal to be measuredand detected. If the desired analytical signal is the intensity of lightradiation absorbed by analytes at each test site F₁–F_(n), absorbancevalues can be calculated in order to determine the concentration of thetarget substance (i.e., the analyte of interest). For this purpose,signal receiving device 230 in FIG. 8 can comprise a UV-visspectrophotometer. The invention, however, is not limited to anyspecific design of spectrophotometer. Possible configurations for thespectrophotometer include those that utilize single detectors ormulti-channel detectors, those that are adapted to perform single-beamor double-beam measurements, those that are adapted to performhorizontal-beam or vertical-beam measurements, and those that canperform measurements of fixed wavelength or of the entire absorptionspectra for the sample. Moreover, for the purpose of the presentdisclosure, the terms “signal receiving device or system” and “sampleanalyzing system” are intended to encompass any analyzing equipmentcompatible with the systems and methods described herein. Such equipmentmay include, but is not limited to, HPLC, spectrometers, photometers,spectrophotometers, spectrographs, and similar equipment. In the case ofa spectrophotometer, signal receiving device 230 typically includeslight source 210, a wavelength selector or similar device, a radiationdetector such as a photoelectric detector or transducer, a signalprocessor, and a readout device.

Referring to the schematic depiction of analytical testing and dataacquisition system 200 illustrated in FIG. 8, light source 210 opticallycommunicates with source line selector device 80 of multiplexingapparatus 10 via input bus IB, and optical signal receiving device 230optically communicates with return line selector device 130 via outputbus OB. In the present embodiment, data encoding system 220 comprises aset of sample measurement components or test sites F₁–F_(n) (e.g., flowcells, sample cells, test vessels, or the like), each of which isadapted to contain or provide a target for a sample to be analyzed.Source line selector device 80 optically communicates with samplemeasurement components F₁–F_(n) via the set of optical source linesOSL₁–OSL_(n), respectively, and return line selector device, 130optically communicates with sample measurement components F₁–F_(n) via aset of optical return lines ORL₁–ORL_(n), respectively. For clarity,only four each of optical source lines OSL₁–OSL_(n), sample measurementcomponents F₁–F_(n) and optical return lines ORL₁–ORL_(n) are shown inFIG. 8. By this arrangement, each sample measurement component F₁–F_(n)can receive an incident light input of an initial intensity P₀ fromlight source over a corresponding optical source line OSL₁–OSL_(n), andsubsequently transmit a light output of an intensity P to optical signalreceiving device for processing and readout over a corresponding opticalreturn line OSL₁–OSL_(n). As described previously, respective internaloptical fibers 90 and 140 of source and return line selector devices 80and 130 are rotatably indexed in mutual synchronization. As a result,the selection of optical source line OSL_(l), for example, to carry thesource signal from internal optical fiber 90 of source line selectordevice 80 to sample measurement component F_(l) concurs with theselection of optical return line ORL_(l) to carry the attenuated signaltransmitted from sample measurement component F_(l) to internal opticalfiber 140 of return line selector device 130.

Referring back to FIG. 3, some of the features of the system describedwith reference to FIG. 8 are schematically shown in operativecommunication with multiplexing apparatus 10. Light source 210 opticallycommunicates with input bus IB, and output bus OB optically communicateswith signal receiving device 230. Sample measurement component F_(l)optically communicates with optical source line OSL, and optical returnline ORL₁. In addition, sample measurement component F_(l) isillustrated in the form of a liquid phase-containing sample holdingcell, and accordingly is illustrated as fluidly communicating with amedia sample line SL₁ and a media return line RL_(l). As describedhereinabove, optical source line OSL_(l) is connected to one of fittings33 of source line selector device 80, and optical return line ORL_(l) isconnected to one of fittings 35 of return line selector device 130. Itwill be understood that other sample measurement components F₂–F_(n) canbe analogously interfaced with multiplexing apparatus 10 and othercorresponding media sample lines and media return lines (not shown).

The operation of sample analysis system 200 with sample cells (e.g.,sample cell or flow cell F_(l) as shown in FIG. 3) will now bedescribed. One or more samples of media are transferred from selectedtest vessels (which could be, for example, mounted in a dissolution testapparatus or other appropriate media preparation/testing apparatus)through media sample lines (e.g., sample line SL₁ in FIG. 3) tocorresponding sample cells F₁–F_(n). After optical measurements aretaken, the samples can be, if the system is so configured, returned tothe test vessels through media return lines (including return line RL,shown in FIG. 3). Calibration operations can also be carried out priorto test runs as needed.

Multiplexing apparatus 10 is operated as described with reference toFIGS. 1–7C. Preferably, the movements of multiplexing apparatus 10 arecoordinated with the operations of the other elements of sample analysissystem 200 under the control of a suitable electronic processing devicesuch as a computer (not shown). Accordingly, source line and return lineselector devices 80 and 130 of multiplexing apparatus 10 are initiallyset to their respective home positions. At the home positions, one ofthe bundle of optical fiber source lines OSL₁–OSL_(n) is positioned(e.g., at “index position 1”) in optical coupling relation with opticalinput bus IB, and a corresponding one of the bundle of optical fiberreturn lines ORL₁–ORL_(n) is positioned (e.g., at a corresponding “indexposition 1”) in optical coupling relation with optical output bus OB. Ineffect, multiplexing apparatus 10 selects the sample measurementcomponent F₁–F_(n) corresponding to the selected index position ofsource and return selector devices 80 and 130.

To take a measurement of the sample residing in the selected samplemeasurement component, light source 210 sends a beam of light ofintensity P₀ into input bus IB. Source line selector device 80 ispositioned such that the light is routed into the selected one of thebundle of source lines OSL₁–OSL_(n). This source beam (or pulse) is thustransmitted into the particular sample measurement component F₁–F_(l)that corresponds to the selected source line OSL₁–OSL_(n) and returnline ORL₁–ORL_(n). Light source 210 and the sample residing in theselected sample measurement component can together be considered as asignal generator, in that light source 210 and the sample conjoin togenerate the analytical signal in the form of an attenuated beam oflight of intensity P as the beam of light passes through the sample. Theanalytical signal is transmitted through the selected one of returnlines ORL₁–ORL_(n) back to multiplexing apparatus 10 and, due to theposition of return line selector device 130, is routed into output busOB. Output bus OB transmits the analytical signal to signal receivingdevice 230 for detection and processing, and the concentration of themeasured sample is determined from the value obtained from its measuredlight absorbance, using calibration curves if necessary.

Within signal receiving device 230, a wavelength selector is typicallyprovided in the form of a filter or monochromator that isolates arestricted region of the electromagnetic spectrum for subsequentprocessing. The detector converts the radiant energy of the analyticalsignal into an electrical signal suitable for use by the signalprocessor. The signal processor can be adapted to modify the transducedsignal in a variety of ways as necessary for the operation of signalreceiving device 230 and the conversion to a readout signal. Functionsperformed by the signal processor can include amplification (i.e.,multiplication of the signal by a constant greater than unity),logarithmic amplification, ratioing, attenuation (i.e., multiplicationof the signal by a constant smaller than unity), integration,differentiation, addition, subtraction, exponential increase, conversionto AC, rectification to DC, comparison of the transduced signal with onefrom a standard source, and/or transformation of the electrical signalfrom a current to a voltage (or the converse of this operation).Finally, a readout device displays the transduced and processed signal,and can be a moving-coil meter, a strip-chart recorder, a digitaldisplay unit such as a digital voltmeter or CRT terminal, a printer, ora similarly related device. As indicated previously, remote flow cellsare but one type of means for encoding information that can be processedby signal receiving device 230. Other examples of sample measurementcomponents are fiber-optic probes, or dip probes, that are designed forinsertion directly into a container holding an analyte-containing media.In some applications, the use of dip probes has been a substitute forthe removal (and preferably the subsequent return) of samples from themedia container and the transfer of the samples to the sample cell of aspectroscopic or other sample analyzing apparatus.

In addition to the use of sample containment means such as flow cells,dip probes and the like as specified hereinabove, other means andaccessories can be employed for generating analytical data in accordancewith the invention. For example, instead of absorption probes,reflectance probes can be employed for undertaking reflectancemeasurements of samples. As appreciated by persons skilled in the art, atypical reflectance probe includes two fiber-optic bundles. One bundleforms a central core and delivers light to the sample. The other bundlesurrounds the central core, and collects the light reflected from thesample and returns it to the detector of the associated sample analyzinginstrument. Alternatively, a transmission probe can be employed toenable the measurement of solid samples. A typical transmission probeincludes two single optical fibers. One fiber delivers light to thesample, and the other collects the light transmitted through the sampleand returns the transmitted light to the sample analyzing instrument.The transmission probe is preferably used in conjunction with a sampleholder adapted to position the sample for measurement. The nature of thesample (e.g., textile fabrics, sunglasses) dictates the design of thesample holder. Transmittance data can also be acquired from solidsamples using an integrating sphere, which is a hollow sphere having aninternal surface that is a non-selective diffuse reflector. Integratingspheres are often used to measure the transmission of turbid,translucent, or opaque refractory materials in situations where othertechniques are inadequate due to loss of light resulting from thescattering effects of the sample.

Referring back to FIGS. 1–3, while input bus IB can be directly coupledto light source 210 and output bus OB directly coupled to signalreceiving device 230, this is not a requirement of the invention. Theinvention contemplates that various accessories and adaptations can beemployed, such as those indicated hereinabove, and that multiplexingapparatus 10 can be integrated with existing analytical systems, inaccordance with specific applications of multiplexing apparatus 10. Forexample, in FIGS. 1–3, multiplexing apparatus 10 can additionallyinclude a fiber-optic coupling unit, generally designated 425, forrouting light beams into and out from fiber-optic cables. Fiber-opticcoupling unit 425 comprises an enclosure 431, fittings 433 and 435mounted to one or more walls of enclosure 431, one or more internaloptical mirrors 437 and 439 (see FIG. 3) disposed within enclosure 431and positioned at desired angles, one or more apertures 441 and 443 (seeFIGS. 1 and 2) formed in the walls of enclosure 431, and various typesof lenses (not shown) if needed. The input end of input bus IB isconnected to fitting 433, and the output end of output bus OB isconnected to fitting 435. As best illustrated in FIG. 3, a source signalfrom light source 210 enters enclosure 431 through aperture 441 (seeFIG. 1), is reflected off internal mirror 437, and is diverted intoinput bus IB. A return signal from output bus OB is reflected offinternal mirror 439 and diverted toward signal receiving device 230through aperture 443 (see FIG. 1).

Referring now to FIGS. 9, 10A, and 10B, another analytical testing anddata acquisition system, generally designated 600, is illustratedaccording to another embodiment of the present invention. In some cases,it may be desirable to eliminate either the multiplexing or thedemultiplexing feature of the invention. Accordingly, this embodimentprovides an alternative multiplexing apparatus, generally designated10′, in which return line selector device 130 has been eliminated.Source line selector device 80 functions as described hereinabove. Inthe present embodiment, multiplexing apparatus 10′ comprises an outputbus mounting assembly 630. Output bus mounting assembly 630 includes anoutput aperture 632 in which a lens 634 is preferably disposed. Lens 634can be situated at the terminal end of a cylindrical collar 636 or othersuitable means for retaining and collecting optical return linesORL₁–ORL_(n) in a fixed-position bundle. In this embodiment, the bundleof optical return lines ORL₁–ORL_(n) collected from, for example,aperture rows 16 or 18 (see FIGS. 2 and 3) is considered in effect to bea multi-channel output bus for analytical testing system 600. The bundleof optical return lines ORL₁–ORL_(n) could also include an extra testline that is connected to a reference source. In FIG. 10A, for example,a total of nine lines are illustrated. For another example, a 16-channelsystem would have seventeen lines (again assuming one test line wereincluded). Output aperture 632 is optically aligned with the receivingwindow of a sample detector SD or other similar analyzing device orlight-receiving component thereof.

In operation, a sample beam from light source 210 is directed throughinput bus IB into the input side of source line selector device 80 inthe manner described hereinabove. As also 30 described hereinabove,source line selector device 80 is indexed by motor 40, shaft 42, gearwheels 45 and 47, and other associated components (see FIGS. 2 and 3) soas to select one of optical source lines OSL₁–OSL_(n). The signal istransferred out from source line selector device 80 through the selectedoptical source line OSL₁–OSL_(n) and associated fitting of one ofaperture rows 16 and 18 to the selected sample container of or othertype of test site F₁–F_(n) of encoding system 220. The transmitted lightbeam P is then returned through the corresponding one of optical returnlines ORL₁ –ORL_(n) through one of aperture rows 16 or 18, to output busmounting assembly 630 where all optical return lines ORL₁–ORL_(n) arebundled at output aperture 632. Transmitted light beam P emanating fromselected optical return line ORL₁ –ORL_(l) is directed into the windowof sample detector SD. This window is large enough to receive light fromany of the ends of optical return lines ORL₁–ORL_(n) bundled at outputbus mounting assembly 630. As an example, the window can beapproximately 1 cm² in area, and the fiber ends of optical return linesORL₁ –ORL_(n) can be positioned approximately 0.5 cm away from thewindow.

It will be noted that multiplexing apparatus 10′, in which either sourceline selector device 80 or return line selector device 130 iseliminated, and either including or not including the other features ofanalytical system 600, can be integrated into the various systems of theinvention described with reference to FIGS. 3 and 8 in the place ofmultiplexing apparatus 10.

It is therefore seen from the foregoing description that the presentinvention provides devices and apparatuses that enable the efficient andcontrolled selection and routing of optical signals and signal pathswith minimal light losses. When utilized in conjunction with samplemeasurement/analysis systems, the embodiments described herein enablehigh-quality analysis and quantification of analytical samples withdecreased effort, expense, and time.

It will be understood that the embodiments described hereinabove can bemodified without undue effort to utilize more than one multiplexingapparatus 10 or 10′, light source 210, signal receiving device 230 orSD, and/or set F of sample measurement components.

It will be further understood that various details of the invention maybe changed without departing from the scope of the invention.Furthermore, the foregoing description is for the purpose ofillustration only, and not for the purpose of limitation—the inventionbeing defined by the claims.

1. An apparatus for selectively coupling fiber optic lines comprising:(a) an optical input selection device rotatable about a first centralaxis and comprising a first input end disposed collinearly with thefirst central axis and a first output end disposed at a radially offsetdistance from the first central axis; (b) an optical output selectiondevice rotatable about a second central axis oriented in non-collinearrelation to the first central axis and comprising a second input enddisposed at a radially offset distance from the second central axis anda second output end disposed collinearly with the second central axis;and (c) a rotatable coupling mechanism interconnecting the optical inputselection device and the optical output selection device.
 2. Theapparatus according to claim 1, comprising a plurality of fiberopticsource lines including respective source line input ends disposed in acircular arrangement, wherein the first output end of the optical inputselection device is selectively optically alignable with each sourceline input end through incremental rotation of the optical inputselection device.
 3. The apparatus according to claim 2, comprising aplurality of fiberoptic return lines including respective return lineoutput ends disposed in a circular arrangement, wherein the second inputend of the optical output selection device is selectively opticallyalignable with each return line output end through incremental rotationof the optical output selection device.
 4. The apparatus according toclaim 1, wherein the optical input selection device comprises: (a) afirst rotary element rotatable about the first central axis; and (b) afirst stationary element disposed adjacent to the first output end andincluding a plurality of circumferentially spaced first apertures,wherein each first aperture is disposed at the radially offset distancefrom the first central axis, and the first output end is alignable witha selected one of the first apertures through rotation of the firstrotary element.
 5. The apparatus according to claim 4, wherein theoptical output selection device comprises: (a) a second rotary elementrotatable about the second central axis; and (b) a second stationaryelement disposed adjacent to the second input end and including aplurality of circumferentially spaced second apertures, wherein eachsecond aperture is disposed at the radially offset distance from thesecond central axis, and the second input end is alignable with aselected one of the second apertures through rotation of the secondrotary element.
 6. The apparatus according to claim 5, wherein the firststationary element includes a first annular section coaxially disposedaround the first rotary element, the second stationary element includesa second annular section coaxially disposed around the second rotaryelement, the optical input selection device includes a first bearingcoaxially interposed between the first rotary element and the firstannular section, and the optical output selection device includes asecond bearing coaxially interposed between the second rotary elementand the second annular section.
 7. The apparatus according to claim 1,wherein the optical input selection device comprises an internal opticalfiber defining an optical path between the first input end and the firstoutput end.
 8. The apparatus according to claim 7, wherein the opticaloutput selection device comprises an internal optical fiber defining anoptical path between the second input end and the second output end. 9.The apparatus according to claim 1, comprising a motor communicatingwith the coupling mechanism for rotating the optical input selectiondevice and the optical output selection device.
 10. An apparatus forselectively coupling fiber optic lines comprising: (a) an optical inputselection device rotatable about a first axis and comprising a firstrotary element having a first internal bore and a first internal opticalfiber extending through the first internal bore; (b) an optical outputselection device rotatable about a second axis and comprising a secondrotary element having a second internal bore and a second internaloptical fiber extending through the second internal bore; and (c) arotatable coupling mechanism interconnecting the optical input selectiondevice and the optical output selection device.
 11. The apparatusaccording to claim 10, wherein the first and second axes arenon-collinear.
 12. The apparatus according to claim 10, wherein thefirst internal optical fiber comprises a first input end disposedcollinearly with the first axis and a first output end disposed at aradially offset distance from the first axis, and the second internaloptical fiber comprises a second input end disposed at a radially offsetdistance from the second axis and a second output end disposedcollinearly with the second axis.
 13. The apparatus according to claim12, wherein the optical input selection device comprises a stationaryelement including a plurality of circumferentially spaced apertures,wherein each aperture is disposed at the radially offset distance fromthe first axis, and the first output end is alignable with a selectedone of the apertures through rotation of the first rotary element. 14.The apparatus according to claim 10, comprising a motor communicatingwith the coupling mechanism for rotating the optical input selectiondevice and the optical output selection device.
 15. A method forselecting an optical channel from a plurality of optical channels,comprising: (a) providing an optical channel selecting device comprisinga rotary member through which an internal bore is formed, the internalbore including an input bore end and an output bore end, whereby therotary member provides an internal optical path running between theinput bore end and the output bore end; and (b) rotating the rotarymember to a position corresponding to a selected optical channel atwhich the internal optical path can optically communicate with acorresponding one of a plurality of optical source lines and acorresponding one of a plurality of optical return lines separate fromthe optical source lines.
 16. The method according to claim 15,comprising transmitting an optical signal from the source linecorresponding to the selected optical channel, to a test site at which asample is exposed to the optical signal, and to the corresponding returnline.
 17. The method according to claim 15, wherein rotating moves theoutput bore end into alignment with the source line corresponding to theselected optical channel, whereby an optical signal can be transmittedfrom the internal optical path to the corresponding source line and thento the corresponding return line.
 18. The method according to claim 17,wherein the output bore end is disposed at a radially offset distancefrom an axis about which the rotary member rotates, and the plurality ofsource lines comprise respective source line input ends fixed in acircumferential arrangement, and rotating the rotary member causes theoutput bore end to rotate about the axis into alignment with the sourceline input end corresponding to the selected optical channel.
 19. Themethod according to claim 17, wherein the optical channel selectingdevice is an optical input selecting device, the rotary member is afirst rotary member, the input bore end is a first input bore end, theoutput bore end is a first output bore end, and the internal opticalpath is a first internal optical path, and the method further comprises:(a) providing an optical output selecting device comprising a secondrotary member through which a second internal bore is formed, the secondinternal bore including a second input bore end and a second output boreend, whereby the second rotary member provides a second internal opticalpath running between the second input bore end and the second outputbore end; and (b) rotating the second rotary member to a positioncorresponding to the selected optical channel at which the second inputbore end is aligned with the return line corresponding to the selectedoptical channel.
 20. The method according to claim 19, comprisingactuating a coupling mechanism interconnecting the optical inputselecting device and optical output selecting device to rotate the firstand second rotary members.
 21. The method according to claim 17, whereinthe plurality of return lines terminate at respective return line outputends mounted in alignment with a signal receiving device, and the methodfurther comprises transmitting an optical signal over the selectedoptical channel whereby the optical signal is sent from the return linecorresponding to the selected optical channel to the signal receivingdevice.
 22. The method according to claim 15, wherein rotating movesinput bore end into alignment with the return line corresponding to theselected optical channel, whereby an optical signal can be transmittedthrough the source line, and then through the return line to theinternal optical path.
 23. The method according to claim 22, comprisingoperating a light source to transmit optical signals through theplurality of source lines, whereby the optical signal transmittedthrough the source line corresponding to the selected optical channel issubsequently transmitted through the return line aligned with the inputbore end and into the internal optical path.
 24. The method according toclaim 22, comprising transmitting the optical signal from the outputbore end to a signal receiving device.